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March 21, 2011 -- Replacing bone marrow with the body’s own stem cells may help patients with aggressive forms of multiple sclerosis (MS) go for years without seeing their disease progress, a new study shows.

Researchers in Greece are following a group of 35 patients who received experimental stem cell transplants for multiple sclerosis.

By purposefully wiping out the immune cells in a patient’s bone marrow with chemotherapy and then repopulating it with healthy stem cells, researchers hope the body’s immune system will stop attacking its own nerves, which eventually become so damaged from MS that they can’t properly transmit signals.

That damage can lead to wide-ranging troubles, including problems with vision, speech, weakness, coordination of movement, numbness, and pain.

According to the National Multiple Sclerosis Society, 400,000 Americans and 2.1 million people worldwide have MS.

Following Stem Cell Transplants in MS

An average of 11 years after their transplants, 25% of the patients in Greece have not seen their disease progress, the researchers report.

Among patients with active lesions on MRI scans before their transplants, indicating that they were in an inflammatory phase of the disease, 44% have not progressed.

Only 10% of patients who went into the study without evidence of ongoing inflammation were able to remain disease free.

Two patients died from transplant-related complications.

“Keeping that in mind, our feeling is that stem cell transplants may benefit people with rapidly progressive MS,” says study researcher Vasilios Kimiskidis, MD, of Aristotle University of Thessaloniki Medical School, Greece, in a news release.

“This is not a therapy for the general population of people with MS but should be reserved for aggressive cases that are still in the inflammatory phase of the disease,” he says.

The study is published in journal Neurology.

“This is the first long-term paper that’s being published on this,” says Richard Nash, MD, an oncologist and member of the Fred Hutchinson Cancer Research Center in Seattle.

Nash is part of a National Institutes of Health trial of stem cell transplants for MS, but he was not involved in the Greek study.

Because patients with MS sometimes go through periods where their disease appears to be dormant before it becomes active again, it can be difficult for researchers to tell if an improvement would have happened naturally or if it is the result of treatment, he explains.

“The progression-free survivals at three, four, and five years in this group were 80%. So they were very high, and people were very hopeful,” Nash says.

Based on this report, however, it now appears that at least some of that early benefit may not have been related to treatment, he says.

But he says the study has helped to better define which patients may respond to stem cells.

Best Candidates for Stem Cell Transplants

Stem cells have long been used to treat cancer patients, but they are still considered experimental in autoimmune diseases like multiple sclerosis.

But many believe they offer great hope.

“It’s the only therapy to date that has been shown to reverse neurologic deficits,” says Richard K. Burt, MD, chief of the division of medicine-immunotherapy for autoimmune diseases at Northwestern University’s Feinberg School of Medicine in Chicago. “But you have to get the right group of patients.”

In Burt’s study, which was published in The Lancet in 2009, 17 out of 21 patients with relapsing-remitting MS improved after stem cell transplants, and none had gotten worse after an average of three years.

As a follow-up to that study, Burt and collaborators in Brazil and Sweden are recruiting patients for a study comparing stem cell transplants to Tysabri, a biologic drug, for the treatment of multiple sclerosis. He is not involved in the current research.

“You have to do it earlier in the disease, that’s where the excitement is, and that’s why we’re doing the randomized trial,” Burt says.

Another article, published in the February issue of Multiple Sclerosis Journal, shows that steps taken before the stem cells are transplanted back into the body may have an effect on how well the procedure works.

Before the stem cells can be reintroduced, patients go through a conditioning process with chemotherapy, either alone or in combination with radiation, in an attempt to wipe out their dysfunctional immune systems. That’s called a high-intensity conditioning regimen.

But a different kind of conditioning, called intermediate-intensity or ”mini” stem cell transplantation, doesn’t try to kill off all of the errant immune system.

“There was a tendency for there to be longer progressive-free survival in the studies that used the intermediate-intensity regimens compared to those that used the high-intensity regimens,” says James T. Reston, PhD, MPH, a research analyst in the Evidence-Based Practice Center at the ECRI Institute in Plymouth Meeting, Pa., an independent, nonprofit group that reviews evidence for experimental therapies.